TW201905070A - Ethylene-vinyl alcohol copolymer composition, pellets and multilayer structure - Google Patents

Abstract

Provided is an ethylene/vinyl alcohol copolymer composition which has satisfactory ultraviolet absorption capacity without any known ultraviolet absorber, has excellent thermal stability, and is inhibited from taking a color. The ethylene/vinyl alcohol copolymer composition comprises an ethylene/vinyl alcohol copolymer (A), a styrene derivative (B), and an iron compound (C), wherein the iron compound (C) is contained in an amount of 0.01-5 weight ppm, in terms of metal amount, of the ethylene/vinyl alcohol copolymer composition.

Description

Ethylene-vinyl alcohol copolymer composition, pellets, and multilayer structure

The present invention relates to an EVOH resin composition having an ethylene-vinyl alcohol copolymer (hereinafter sometimes referred to as "EVOH resin") as a main component, pellets made of the EVOH resin composition, and multilayers having a layer made of the same. The structure, more specifically, relates to an EVOH resin composition having ultraviolet absorbing ability, pellets composed of the EVOH resin composition, and a multilayer structure having a layer composed of the EVOH resin composition.

EVOH resin has excellent transparency, gas barrier properties such as oxygen, flavor retention, solvent resistance, oil resistance, mechanical strength, etc. It is formed into films, sheets, bottles, etc. and widely used as food packaging materials and pharmaceuticals Packaging materials, industrial pharmaceutical packaging materials, pesticide packaging materials, and other packaging materials.

However, many foods, medicines, and the like are degraded or deteriorated by ultraviolet rays, and there is a need for packaging materials to have ultraviolet absorption capacity. As a method for imparting ultraviolet absorbing ability to a packaging material, an ultraviolet absorbent is generally blended with a resin used as a packaging material. For example, some people have proposed a laminated structure obtained by laminating a layer of polyolefin and EVOH resin, and mixing a part or all of the layer with an ultraviolet absorbent to reduce the ultraviolet transmittance (for example, refer to the patent Reference 1). [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2008-230112

[Problems to be Solved by the Invention]

However, the ultraviolet absorber is generally a low-molecular compound, and therefore it is easy to migrate in the resin after it becomes a molded product, and there are problems in that it migrates to the surface of the layer during use, contacts the contents, or makes the surface sticky. In addition, in order to obtain a sufficient ultraviolet absorbing ability, a large amount of ultraviolet absorbent must be blended in the resin, as a result, the resin characteristics tend to be lowered.

When the inventors of the present invention solved this problem and obtained an EVOH resin composition having a good ultraviolet absorption ability without incorporating a known ultraviolet absorber, they thought of using an iron compound. However, when an iron compound is blended in the EVOH resin composition, the ultraviolet absorption capacity and thermal stability are increased in proportion to the blending amount, but there is a tendency to be colored during melt molding.

That is, the present invention provides an EVOH resin composition, pellets, and multilayer structures that have ultraviolet absorption ability, are excellent in thermal stability, and have suppressed coloration even if a known ultraviolet absorbent is not blended. [Means for solving problems]

In view of the above-mentioned facts, the inventors of the present case made efforts to find out, and as a result, they found that by using a specific amount of an iron compound and a styrene derivative (B) for the EVOH resin, the obtained resin composition has ultraviolet absorption ability, excellent thermal stability, and color Suppressed to complete the present invention.

That is, the first gist of the present invention is an EVOH resin composition containing an EVOH resin (A), a styrene derivative (B), and an iron compound (C), and is characterized in that the EVOH resin composition per unit weight is The content of the iron compound (C) is 0.01 to 5 ppm in terms of metal. The second gist of the present invention is a pellet composed of the EVOH resin composition. The third gist of the present invention is a multilayer structure having a layer composed of the EVOH resin composition. [Effect of the invention]

The EVOH resin composition of the present invention contains an EVOH resin (A), a styrene derivative (B), and an iron compound (C), and the content of the iron compound (C) per unit weight of the EVOH resin composition is converted to metal Counted as 0.01 ~ 5ppm. Therefore, the EVOH resin composition of the present invention does not use an ultraviolet absorbent that is suspected of surface migration and hinders the characteristics of the resin, but still has ultraviolet absorption ability, is excellent in thermal stability, and can suppress coloring during heating.

In addition, in the present invention, especially when the content of the styrene derivative (B) per unit weight of the EVOH resin composition is 1 to 1000 ppm, it can have more excellent ultraviolet absorption ability and thermal stability, and it can be heated. The color is more suppressed.

Furthermore, in the present invention, in particular, if the weight ratio of the content of the styrene derivative (B) to the metal-converted content of the iron compound (C) is 0.2 to 50,000, it can have more excellent ultraviolet absorption capacity and heat. Stability, and the color is more suppressed when heated.

In addition, the pellets composed of the EVOH resin composition of the present invention have ultraviolet absorption ability, are excellent in thermal stability, and suppress coloring during heating, so they can be used as raw materials for packaging materials.

In addition, a multilayer structure having a layer containing the EVOH resin composition of the present invention has ultraviolet absorbing ability, is excellent in thermal stability, and suppresses coloring during heating, and is therefore particularly useful as a packaging material for foods.

The following is a detailed description of the constitution of the present invention, but these are examples of ideal implementation modes and are not limited to these contents.

The EVOH resin composition of the present invention contains EVOH resin (A) as a main component, and contains a styrene derivative (B) and an iron compound (C). The base resin of the EVOH resin composition of the present invention is an EVOH resin (A). That is, the content of the EVOH resin (A) in the EVOH resin composition is usually 70% by weight or more, preferably 80% by weight or more, more preferably 90% by weight or more, and particularly preferably 95% by weight or more. Each component is explained below.

[EVOH resin (A)] The EVOH resin (A) used in the present invention is generally a resin obtained by saponifying an ethylene-vinyl ester copolymer which is a copolymer of ethylene and a vinyl ester monomer, and is non-aqueous. Thermoplastic resin. In terms of the above vinyl ester monomers, vinyl acetate is generally used in consideration of economic aspects. As for the polymerization method of ethylene and vinyl ester monomers, any known polymerization method such as solution polymerization, suspension polymerization, emulsion polymerization, and the like can be used and implemented. Generally, solution polymerization using methanol as a solvent is used. The saponification of the obtained ethylene-vinyl ester copolymer can also be performed by a well-known method. The EVOH resin (A) produced in the above manner is mainly composed of structural units derived from ethylene and structural units derived from vinyl alcohol, and contains a small amount of vinyl ester structural units remaining unsaponified.

As the above-mentioned vinyl ester-based monomer, vinyl acetate is typically used in view of market availability and the viewpoint of good impurity treatment efficiency during manufacture. Examples of other vinyl ester-based monomers include vinyl formate, vinyl propionate, vinyl valerate, vinyl butyrate, vinyl isobutyrate, vinyl trimethyl acetate, vinyl caprate, and lauric acid. Ethyl vinyl ester, vinyl stearate, vinyl tertiary carbonate and other aliphatic vinyl esters, aromatic benzoic esters such as vinyl benzoate, etc. can be used usually 3 to 20 carbon atoms, preferably 4 to 10 carbon atoms, especially It is preferably an aliphatic vinyl ester having 4 to 7 carbon atoms. These are usually used alone, but multiple types can be used at the same time if necessary.

The content of the ethylene structural unit in the EVOH resin (A) can be controlled by the pressure of ethylene when the vinyl ester monomer is copolymerized with ethylene, and is usually 20 to 60 mol%, preferably 25 to 50 mol. Ear%, especially good for 28 ~ 45 mole%. When the content is too low, gas barrier properties and elongation tend to decrease under high humidity; on the contrary, when the content is too high, gas barrier properties tend to decrease. The content of the ethylene structural unit can be measured in accordance with ISO14663.

The degree of saponification of the vinyl ester component in the EVOH resin (A) can be determined by the amount, temperature, time, etc. of the saponification catalyst (usually using a basic catalyst such as sodium hydroxide) when saponifying an ethylene-vinyl ester copolymer The control is usually 90 to 100 mole%, preferably 95 to 100 mole%, and particularly preferably 99 to 100 mole%. When the saponification degree is too low, gas barrier properties, thermal stability, moisture resistance, and the like tend to decrease. The degree of saponification of the EVOH resin (A) can be measured in accordance with JIS K6726 (the EVOH resin is used in the form of a solution in which it is uniformly dissolved in a water / methanol solvent).

The melt flow rate (MFR) of the EVOH resin (A) (210 ° C, load: 2160 g) is usually 0.5 to 100 g / 10 minutes, preferably 1 to 50 g / 10 minutes, and particularly preferably 3 to 35 g / 10 minutes. When the MFR is too large, the stability during film formation tends to be impaired. When the MFR is too small, the viscosity tends to become too high and melt extrusion becomes difficult. The MFR is an indicator of the degree of polymerization of the EVOH resin, and can be adjusted by the amount of a polymerization initiator and the amount of a solvent when ethylene and a vinyl ester-based monomer are copolymerized.

The EVOH resin (A) used in the present invention may further contain a structural unit derived from a comonomer as shown below within a range that does not hinder the effects of the present invention (for example, 10 mol% or less of the EVOH resin (A)). Examples of the comonomer include olefins such as propylene, 1-butene, and isobutene, 3-butene-1-ol, 3-butene-1,2-diol, and 4-pentene-1 -Alcohol, 5-hexene-1,2-diol, and other hydroxyl-containing α-olefins or derivatives thereof, such as esterified products and fluorenated compounds; 2-methylenepropane-1,3-diol, 3- Hydroxyalkyl vinylenes such as methylenepentane-1,5-diol; 1,3-diethoxy-2-methylenepropane, 1,3-dipropoxy-2 Methylpropane, 1,3-dibutyryloxy-2-methylenepropane and other hydroxyalkyl vinylene diacetates; acrylic acid, methacrylic acid, crotonic acid, phthalic acid (anhydride), maleic acid Unsaturated acids such as (anhydride), itaconic acid (anhydride) or their salts, or mono- or dialkyl esters with 1 to 18 carbons; acrylamide, N-alkylacrylamide with 1 to 18 carbons Acrylamides such as N, N-dimethylacrylamide, 2-acrylamine propanesulfonic acid or its salt, acrylamide propyldimethylamine or its acid salt or its fourth-order salt; methyl Acrylamide, N-alkyl methacrylamide with 1 to 18 carbon atoms, N, N-dimethylmethacrylamide, 2-methacrylamine propanesulfonic acid or its salt, methacryl Aminopropyldi Methacrylamide, such as methylamine or its acid salt, or its fourth-order salt; N-vinylfluorenamines, such as N-vinylpyrrolidone, N-vinylformamide, and N-vinylacetamide; propylene Vinyl cyanide such as nitrile and methacrylonitrile; vinyl ethers such as alkyl vinyl ether, hydroxyalkyl vinyl ether, alkoxyalkyl vinyl ether with 1 to 18 carbons; vinyl chloride, vinylidene chloride, vinyl fluoride , Vinylidene fluoride, vinyl bromide and other halogenated ethylene compounds; trimethoxy vinyl silanes and other vinyl silanes; allyl acetate, chloropropylene and other halogenated allyl compounds; allyl alcohol, dimethoxyene Allyl alcohols such as propanol; comonomers such as trimethyl- (3-acrylamido-3-dimethylpropyl) -ammonium chloride and acrylamine-2-methylpropanesulfonic acid. These can be used individually or in combination of 2 or more types.

In particular, considering the point that the gas barrier property is maintained and the secondary formability is good at the same time, an EVOH resin having a primary hydroxyl group in a side chain is preferred, and among them, EVOH obtained by copolymerizing a hydroxyl-containing α-olefin A resin is preferred, and an EVOH resin having a 1,2-diol structure in a side chain is particularly preferred. In particular, in the case of an EVOH resin having a primary hydroxyl group in a side chain, the content of the structural unit derived from a monomer having the primary hydroxyl group is usually 0.1 to 20 mol%, and more preferably 0.5 to 15 mol. %, Particularly preferred is 1 to 10 mole%.

In addition, the EVOH resin (A) used in the present invention may be obtained by "post-modification" such as urethanization, acetalization, cyanoethylation, and oxyalkylation.

In addition, the EVOH resin (A) used in the present invention may be a mixture with other EVOH resins. As the other EVOH resins, there may be mentioned those having different contents of ethylene structural units, those having different degrees of saponification, and those having different degrees of polymerization. Those with different polymerization components.

[Styrene Derivative (B)] The styrene derivative (B) used in the present invention refers to an aromatic compound capable of resonance stabilization and capture of radicals, and specifically has a styrene molecular structure A compound that acts as a molecular backbone. A styrene compound having a substituent at the α-position or the β-position is preferred.

For example, a styrene compound having a substituent at the α position is preferred from the viewpoint of using a benzyl position to stabilize the radical by resonance. Specific examples include 2,4-diphenyl-4-methyl-1-pentane. Olefin and so on. When the styrene compound having a substituent at the β-position is a styrene compound having a carbonyl group at the β-position, it is preferable from the viewpoint of having an enone structure to stabilize the radical by resonance. Examples include cinnamic acid and cinnamon Cinnamate derivatives such as acid alcohol, cinnamate, and cinnamate. Among them, the use of cinnamic acid is the most ideal.

The molecular weight of the styrene derivative (B) is usually 100 to 100,000, preferably 100 to 10,000, particularly preferably 100 to 1,000, and extremely preferably 130 to 300. When the molecular weight is within the above range, the effect of the present invention tends to be more effectively obtained.

The content of the styrene derivative (B) is usually 1 to 1000 ppm, preferably 10 to 800 ppm, and particularly preferably 50 to 600 ppm based on the entire EVOH resin composition of the present invention. When it is too large, productivity tends to decrease; when it is too small, thermal stability tends to decrease.

In addition, the EVOH resin composition serving as a reference for the content ratio of the styrene derivative (B) is an EVOH resin (A), a styrene derivative (B), an iron compound (C), and is blended as necessary. Various additives, such as EVOH resin compositions, as final products.

The content of the styrene derivative (B) in the EVOH resin composition of the present invention can be measured by, for example, liquid chromatography mass spectrometry (LC / MS / MS) according to the following procedure. The following procedures are described using cinnamic acid as an example. However, the same procedures can be performed for other styrene derivatives (B).

<Method for measuring the content of styrene derivative (B)> [Preparation of standard solution] Weigh cinnamic acid (10.89mg) into a 10mL dosing bottle and dissolve it in methanol to make a 10mL solution (standard stock solution; 1089μg / mL). Next, the prepared standard stock solution was diluted with methanol to prepare each mixed standard solution at multiple concentrations (0.109 μg / mL, 0.218 μg / mL, 0.545 μg / mL, 1.09 μg / mL, 2.18 μg / mL). LC / MS / MS analysis was performed using these mixed standard solutions to prepare a calibration curve.

[Preparation of sample solution] (1) The pulverized pellets (1 g) of the EVOH resin composition of the present invention were weighed into a 10 mL measuring bottle, and then 9 mL of methanol was added. (2) After performing ultrasonic treatment for 120 minutes, it was left to cool at room temperature (25 ° C). (3) Add methanol and make up to 10 mL (sample solution (I)). (4) Take 1 mL of the sample solution (I) into a 10 mL dosing bottle, then add methanol and make up to 10 mL (sample solution (II)). (5) A liquid obtained by filtering the sample solution (I) or the sample solution (II) through a PTFE filter (0.45 μm) as a measurement solution for analysis by LC / MS / MS. The detection concentration of cinnamic acid was calculated from the peak area value obtained by LC / MS / MS analysis and the calibration curve of the standard solution.

[LC / MS / MS measurement conditions] LC system: LC-20A [manufactured by Shimadzu Corporation] Mass spectrometer: API4000 [AB / MDS Sciex] Analytical column: Scherzo SM-C18 (3.0 × 75mm, 3μm) Column temperature ： 45 ℃ Mobile phase: A 10mmol / L ammonium acetate solution B Methanol time program: 0.0 → 5.0min B% = 30% → 95% 5.0 → 10.0min B% = 95% 10.1 → 15.0min B% = 30% Flow rate: 0.4mL / min Switching valve: 2.0 to 6.0min: to MS Injection volume: 5μL Ionization: ESI detection: Negative ion detection (SRM method) Monitoring ions: Q1 = 147.0 → Q3 = 102.9 (CE: -15eV)

[Iron compound (C)] The present invention is characterized by containing an EVOH resin (A), a styrene derivative (B), and an iron compound (C), and the blending amount of the iron compound (C) is a specific trace amount. By adopting this structure, it was found that the obtained resin composition has ultraviolet absorbing ability, is excellent in thermal stability, and suppresses coloration.

In addition, the iron compound (C) may exist in the form of oxides, hydroxides, chlorides, or iron salts in the EVOH resin composition, or it may be in an ionized state, or in combination with resins or other materials. The state of the complex formed by the interaction of the seats exists. Examples of the oxide include iron (III) oxide, triiron tetroxide, and ferrous oxide. Examples of the chloride include iron (II) chloride and iron (III) chloride. Examples of the hydroxide include iron (II) hydroxide and iron (III) hydroxide. Examples of the iron salt include inorganic salts such as iron phosphate and iron sulfate, and organic salts such as iron such as carboxylic acid (acetic acid, butyric acid, and stearic acid). These can be used individually or in combination of 2 or more types.

From the viewpoint of dispersibility in the EVOH resin composition, the iron compound (C) is preferably water-soluble. From the viewpoint of dispersibility and productivity, the molecular weight is usually 100 to 10,000, preferably 100 to 1,000, and particularly preferably 100 to 500.

The EVOH resin composition of the present invention is characterized in that the content of the iron compound (C) per unit weight of the EVOH resin composition is 0.01 to 5 ppm in terms of metal. The content of the iron compound is preferably 0.05 to 3 ppm, and particularly preferably 0.08 to 1 ppm. If the content of the iron compound is too small, the ultraviolet absorbing ability tends to decrease; if it is too large, the molded product tends to be colored.

Here, the content of the iron compound (C) refers to a content measured by the following method. <Analysis of iron compound (C)> 0.5 g of the pulverized product of EVOH resin composition pellets was subjected to an ashing treatment at 650 ° C for 1 hour in an oxygen gas stream using an infrared heating furnace, and the ash was dissolved in an acid and fixed with pure water. This was used as a sample solution. This solution was measured using an ICP mass spectrometer 7500ce manufactured by Agilent Technologies, and was measured according to the ICP-MS standard addition method.

The weight ratio of the content of the styrene derivative (B) to the metal conversion content of the iron compound (C) in the EVOH resin composition of the present invention is usually 0.2 to 50,000, preferably 1 to 20,000, and particularly preferably 100 ~ 10000, preferably 1000 ~ 8000. When the value is too large, the ultraviolet absorbing ability tends to be low; when it is too small, the molded article tends to be colored.

[Other thermoplastic resins] The EVOH resin composition of the present invention may be in a range that does not hinder the effects of the present invention (for example, it is usually 30% by weight or less, preferably 20% by weight or less, and particularly preferably 10% by weight of the EVOH resin composition). % By weight or less) Contains thermoplastic resin other than EVOH resin (A). As for other thermoplastic resins, known thermoplastic resins can be used. Specific examples include polyamine resin, polyolefin resin, polyester resin, polystyrene resin, polyvinyl chloride resin, polycarbonate resin, polyacrylic resin, ionic polymer, and ethylene- Acrylic copolymer, ethylene-acrylate copolymer, ethylene-methacrylic copolymer, ethylene-methacrylate copolymer, polyvinylidene chloride, vinyl ester resin, polyester elastomer, polyurethane elasticity Body, chlorinated polyethylene, chlorinated polypropylene, etc. These can be used individually or in combination of 2 or more types.

[Other admixtures] Furthermore, the EVOH resin composition of the present invention may contain a blending agent generally blended in an EVOH resin within a range that does not prevent the effect of the present invention. For example, inorganic double salts (such as magnesite, etc.), plasticizers (such as aliphatic polyhydric alcohols such as ethylene glycol, glycerin, and hexanediol), and oxygen absorbers [such as aluminum powder, Inorganic oxygen absorbents such as potassium sulfate and photocatalyst titanium oxide; ascorbic acid, and its fatty acid esters or metal salts, hydroquinone, gallic acid, hydroxyl-containing phenolic resins, polyphenols, and salicylaldehyde-imide cobalt , Nitrogen compounds such as tetraethylenepentaamine, cobalt-Schiff base complexes, porphyrins, macrocyclic polyamine complexes, polyethyleneimine-cobalt complexes, and transition metals other than iron Coordination compounds, terpene compounds, reaction products of amino acids and hydroxyl-containing reducing substances, organic compounds such as triphenylmethyl compounds, oxygen absorbers; coordination of nitrogen-containing resins with transition metals other than iron Combinations (e.g., m-xylylene diamine (MXD) nylon and cobalt), blends of tertiary hydrogen-containing resins and transition metals other than iron (e.g., polypropylene and cobalt), carbon-carbon Blends of saturated-bond resins with transition metals other than iron (e.g., a combination of polybutadiene and cobalt ), Photooxidative degradable resin (such as polyketone), onion quinone polymer (such as polyvinyl onion quinone), etc., and a photoinitiator (benzophenone, etc.) is further added to the blend, and other than the above Antioxidant or deodorant (active carbon, etc.) made of polymer-based oxygen absorbers], heat stabilizers, light stabilizers, ultraviolet absorbers, colorants, antistatic agents, surfactants (but as lubricants (Except agent users), antibacterial agents, anti-blocking agents, fillers (such as inorganic fillers, etc.). These compounds can be used alone or in combination of two or more.

[Manufacturing method of EVOH resin composition] As a method for manufacturing the EVOH resin composition of the present invention, for example, a known method such as a dry blending method, a melt mixing method, a solution mixing method, and an impregnation method may be mentioned. And other methods are arbitrarily combined.

Examples of the dry blending method include (i) a method of dry blending EVOH resin (A) pellets, styrene derivatives (B), and iron compounds (C) using a roller or the like.

For the melt-mixing method, for example, (ii) melt-kneading dry blends of EVOH resin (A) pellets, styrene derivatives (B), and iron compounds (C) to obtain pellets or A method of forming a product; (iii) a method of adding a styrene derivative (B) and an iron compound (C) to the EVOH resin (A) in a molten state, followed by melt-kneading to obtain pellets or a molded product, and the like.

For the solution mixing method, for example, (iv) a commercially available EVOH resin (A) pellet is used to prepare a solution, and at least one of the styrene derivative (B) and the iron compound (C) is blended in the solution. One is a method of solidifying, forming, granulating, and drying after solid-liquid separation; (v) in the manufacturing process of EVOH resin (A), the ethylene-vinyl ester copolymer solution before saponification, the EVOH resin A method in which a homogeneous solution (water / alcohol solution, etc.) contains at least one of a styrene derivative (B) and an iron compound (C), is solidified, formed, granulated, and subjected to solid-liquid separation and then dried.

Examples of the impregnation method include: (vi) bringing EVOH resin (A) pellets into contact with an aqueous solution containing at least one of a styrene derivative (B) and an iron compound (C), and bringing the EVOH resin (A ) A method of drying the pellet after containing at least one of the styrene derivative (B) and the iron compound (C).

In addition, (vii) a gear pump or the like is used to transport a methanol solution of the EVOH resin (A) containing a high concentration of a non-oxidizing acid (for example, hydrochloric acid, acetic acid), so that a small amount of the iron compound (C) is removed from The stainless steel of the driving part of the gear pump is eluted, and a small amount of the iron compound (C) is mixed with the EVOH resin (A). EVOH resin (A) pellets containing the EVOH resin (A) and the iron compound (C) are obtained from the methanol solution of the EVOH resin (A) after the treatment, and the EVOH resin (A) pellets containing the iron compound (C) are obtained. A method of obtaining pellets by dry blending and melt-kneading at least one of the pellets and the styrene derivative (B); or containing the EVOH resin (A) pellets of the iron-containing compound (C) by an impregnation method A method of obtaining a pellet by drying the styrene derivative (B), and the like.

In the present invention, the different methods described above may be combined. Among them, considering the viewpoint of productivity, it is desirable to make the ethylene-vinyl ester copolymer solution before saponification contain a styrene derivative (B), and use a conventional method to perform saponification, and use water as needed for the obtained EVOH resin (A) solution. A method of adjusting a solvent and supplying the EVOH resin (A) solution to (vii). Furthermore, from the viewpoint of productivity and obtaining a resin composition having a more significant effect of the present invention, the melt-mixing method is preferable, and the method (ii) is particularly preferable.

In addition, the shape of the EVOH resin composition pellets of the present invention obtained by the above methods and the EVOH resin (A) pellets used in each method are arbitrary. For example, there are spherical, oval, cylindrical, cubic, rectangular parallelepiped, etc., usually oval or cylindrical. As far as its size is concerned, the point of view of the convenience when used as a molding material is the short diameter when it is oval. It is usually 1 to 10 mm, preferably 2 to 6 mm, more preferably 2.5 to 5.5 mm, and the long diameter is usually 1.5 to 30 mm, preferably 3 to 20, and more preferably 3.5 to 10 mm. In the case of a cylindrical shape, the diameter of the bottom surface is usually 1 to 6 mm, preferably 2 to 5 mm, and the length is usually 1 to 6 mm, preferably 2 to 5 mm.

In addition, as the iron compound (C) used in each of the above methods, as described above, a water-soluble iron compound is preferably used, and examples thereof include oxides such as iron (III) oxide, triiron tetroxide, and ferrous oxide, and iron chloride ( II), chlorides such as iron (III) chloride, hydroxides such as iron (II) hydroxide, iron (III) hydroxide, inorganic salts such as iron phosphate and iron sulfate, carboxylic acids (acetic acid, butyric acid, stearic acid) Acid, etc.) iron salts such as organic salts such as iron. In addition, as described above, the iron compound (C) may be ionized in the EVOH resin composition in the form of the salt, or may be formed by using resin or other compounds as ligands. The state of the compound exists.

In the aqueous solution containing the iron compound (C) used in the method (vi) above, the aqueous solution of the iron compound (C) can be used to immerse iron in a steel material by immersing it in water containing various agents. Produced by ion dissolution. In addition, at this time, the content (metal conversion) of the iron compound (C) in the EVOH resin composition can be controlled by the concentration of the iron compound in the aqueous solution of the EVOH resin (A) pellets, the immersion temperature, and the immersion time. . The dipping time is usually 0.5 to 48 hours, preferably 1 to 36 hours, and the dipping temperature is usually 10 to 40 ° C, preferably 20 to 35 ° C. This EVOH resin composition pellet was subjected to solid-liquid separation by a known method, and dried by a known drying method. The drying method may be any of various drying methods, and may be any one of standing drying and flowing drying. Moreover, these may be combined and implemented.

The moisture content of the pellets of the EVOH resin composition of the present invention is usually 0.01 to 0.5% by weight, preferably 0.05 to 0.35% by weight, and particularly preferably 0.1 to 0.3% by weight.

The water content of the pellets of the EVOH resin composition of the present invention is measured and calculated by the following method. Use an electronic balance to measure the weight before drying of the EVOH resin composition pellets (W1), dry them in a hot air drier at 150 ° C for 5 hours, and place them in the dryer for 30 minutes to cool and weigh (W2), according to the following formula Figure it out. Moisture content (% by weight) = [(W1-W2) / W1] × 100

The pellets of the EVOH resin composition obtained in this way can be directly used for melt molding, but in view of stabilizing the feedability during melt molding, it is also preferable to attach a known lubricant to the surface of the pellets. Examples of the type of lubricant include higher fatty acids having a carbon number of 12 or more (for example, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, etc.), higher fatty acid esters ( For example, methyl esters, isopropyl esters, butyl esters, octyl esters of higher fatty acids, saturated fatty acids such as laurylamine, myristylamine, palmitylamine, stearylamine, behenylamine, etc. Unsaturated fatty fatty amines such as oleylamine, erucamide, ethylidenestearylamine, ethylidene oleylamine, ethylidyl erosamine, ethylidene laurel Bisamines such as ammonium amines, etc.), low molecular weight polyolefins (for example, low molecular weight polyethylene or low molecular weight polypropylene with a molecular weight of about 500 to 10,000, etc., or acid-modified products thereof), higher alcohols with a carbon number of 6 or more, Ester oligomers, fluorinated ethylene resins, etc. These compounds can be used alone or in combination of two or more. The content of the lubricant is usually 5% by weight or less, preferably 1% by weight or less, of the EVOH resin composition.

The EVOH resin composition of the present invention obtained in this way is prepared into various types of EVOH resin compositions such as pellets, powders, and liquids, and is provided as a molding material for various moldings. In particular, in the present invention, when it is provided as a material for melt molding, the effect of the present invention tends to be more effectively obtained, which is preferable. The EVOH resin composition of the present invention also includes a resin composition obtained by mixing a resin other than the EVOH resin (A) used in the EVOH resin composition of the present invention.

The molded article can be provided in the form of a single-layer film formed by using the EVOH resin composition of the present invention, or a multilayer structure having a layer formed by using the EVOH resin composition of the present invention. For practical.

[Multilayer Structure] The multilayer structure of the present invention has a layer composed of the EVOH resin composition of the present invention described above. The layer containing the EVOH resin composition of the present invention (hereinafter simply referred to as "EVOH resin composition layer"), and other base materials (the following are mainly based on a thermoplastic resin other than the EVOH resin composition of the present invention as a main component) The resin used in the base material is simply referred to as "base material resin.") Lamination can further impart strength, protect the EVOH resin composition layer from moisture, and other functions.

Examples of the base resin include linear low-density polyethylene, low-density polyethylene, ultra-low-density polyethylene, medium-density polyethylene, high-density polyethylene, and ethylene-propylene (block and random). Polyethylene resins such as copolymers, ethylene-α-olefin (α-olefins with 4 to 20 carbons) copolymers, polypropylene, polypropylene, propylene-α-olefins (α-olefins with 4 to 20 carbons) copolymers, etc. (Unmodified) polyolefin resins such as propylene-based resins, polybutene, polypentene, polycyclic olefin-based resins (polymers having a cyclic olefin structure in at least one of the main chain and side chains), the Polyolefins such as unsaturated carboxylic acid-modified polyolefin-based resins obtained by graft modification with unsaturated carboxylic acids or their esters, and other modified olefin-based resins, such as polyolefin resins, ionic polymers, and ethylene- Vinyl acetate copolymers, ethylene-acrylic acid copolymers, ethylene-acrylic acid ester copolymers, polyester resins, polyamide resins (including copolymerized polyamides), polyvinyl chloride, polyvinylidene chloride, acrylic acid Resin, polystyrene resin, vinyl ester resin, polyester elastomer, polyurethane Ester-based elastomers, polystyrene-based elastomer, chlorinated polyethylene, chlorinated polypropylene, halogenated polyolefin, an aromatic or aliphatic poly-ketones.

Among these, polyamine-based resins, polyolefin-based resins, polyester-based resins, and polystyrene-based resins which are hydrophobic resins are preferred, and polyethylene-based resins, polypropylene-based resins, and polycyclic resins are more preferred. Polyolefin resins such as olefin-based resins and unsaturated carboxylic acid-modified polyolefin resins.

The multilayer structure of the multilayer structure can be a / b when the EVOH resin composition layer of the present invention is a (a1, a2, ･ ･ ･) and the base resin layer is b (b1, b2, ･ ･ ･). , B / a / b, a / b / a, a1 / a2 / b, a / b1 / b2, b2 / b1 / a / b1 / b2, b2 / b1 / a / b1 / a / b1 / b2, etc. Of combination. In addition, the mixture containing the EVOH resin composition of the present invention and a thermoplastic resin other than the EVOH resin composition of the present invention is obtained by remelting the ends, defective products, and the like generated in the process of manufacturing the multilayer structure. When the reproduction layer is R, it can also be b / R / a, b / R / a / b, b / R / a / R / b, b / a / R / a / b, b / R / a / R / a / R / b, etc. The number of layers of the multilayer structure is usually 2-15, and preferably 3-10. If necessary, an adhesive resin layer containing an adhesive resin may be interposed between each of the above-mentioned layers.

The above-mentioned adhesive resin may be a known one, and it may be appropriately selected depending on the type of the thermoplastic resin used in the base resin "b". Typical examples include carboxyl-containing modified polyolefin-based polymers obtained by chemically bonding an unsaturated carboxylic acid or its anhydride to a polyolefin-based resin by an addition reaction, a graft reaction, or the like. Examples of the carboxyl group-containing modified polyolefin-based polymer include maleic anhydride graft-modified polyethylene, maleic anhydride graft-modified polypropylene, and maleic anhydride graft-modified ethylene-propylene (block And random) copolymers, maleic anhydride grafted modified ethylene-ethyl acrylate copolymers, maleic anhydride grafted modified ethylene-vinyl acetate copolymers, maleic anhydride modified polycyclic olefin resins, horses Anhydride graft modified polyolefin resin and the like. Further, a mixture of one or more selected from these may be used.

In a multilayer structure, when an adhesive resin layer is used between the EVOH resin composition layer and the substrate resin layer of the present invention, the adhesive resin layers are positioned on both sides of the EVOH resin composition layer, so it is preferable to use an excellent hydrophobicity. Adhesive resin.

The base resin and the adhesive resin may contain conventional plasticizers and fillers within a range that does not interfere with the gist of the present invention (for example, 30% by weight or less, preferably 10% by weight or less with respect to the entire resin). , Clay (montmorillonite, etc.), colorants, antioxidants, antistatic agents, lubricants, nucleating agents, anti-blocking agents, waxes, etc. These can be used individually or in combination of 2 or more types.

The lamination of the EVOH resin composition layer of the present invention and the base resin layer (including the case where the adhesive resin layer is interposed) can be implemented by a known method. Examples include: a method of melt-extruding a base resin into a film, sheet, etc. of the EVOH resin composition of the present invention; a method of melt-extruding an EVOH resin composition of the present invention on a base resin layer; Method for coextrusion of EVOH resin composition and base resin; use known adhesives such as organic titanium compounds, isocyanate compounds, polyester compounds, polyurethane compounds, etc. A method of dry-laminating a resin (layer); a method of removing a solvent after coating a solution of an EVOH resin composition on a base resin, and the like. Among these, it is better to consider the cost and environment viewpoints, and to carry out co-extrusion.

As described above, the multilayer structure may be subjected to (heating) stretching treatment if necessary. The extension treatment may be any of uniaxial extension and biaxial extension. When the biaxial extension is performed, the extension may be performed simultaneously or successively. As for the stretching method, a roll stretching method, a tenter stretching method, a tubular stretching method, a stretch blow molding method, a vacuum pressure forming method, or the like may be used. The elongation temperature is a temperature near the melting point of the multilayer structure, and is usually selected from the range of about 40 to 170 ° C, preferably from the range of about 60 to 160 ° C. When the elongation temperature is too low, the elongation becomes poor; when it is too high, it is difficult to maintain a stable elongation state.

In order to provide dimensional stability after stretching, heat fixation may be performed. The heat fixation can be performed by a known method. For example, the stretched film is heat treated at a temperature of usually 80 to 180 ° C, preferably 100 to 165 ° C, and usually a heat treatment of about 2 to 600 seconds. In addition, when the multilayer stretched film obtained from the EVOH resin composition of the present invention is used as a shrinkable film, in order to provide heat shrinkability, the heat-fixing is not performed, and, for example, cooling and fixing are performed by blowing cold air on the stretched film. Just fine.

Moreover, you may use a multilayer structure of this invention to obtain a cup-shaped and tray-shaped multilayer container as needed. At this time, a draw forming method is usually used, and specific examples include a vacuum forming method, a pressure forming method, a vacuum pressure forming method, a plunger-assisted vacuum pressure forming method, and the like. In addition, when a tube or bottle-shaped multilayer container (layered structure) is obtained from a multilayer type (a hollow tubular preform before blow molding), a blow molding method is used. Specific examples include: extrusion blow molding (double-head type, mold moving type, die moving type, rotary type, accumulation type, horizontal bad type, etc.), cold parison type blow molding method, injection blow molding Method, biaxial extension blow molding method (extruded cold parison biaxial extension blow molding method, injection cold parison biaxial extension blow molding method, injection molding embedded biaxial extension blow molding method, etc. )Wait. The obtained laminated body can be subjected to heat treatment, cooling treatment, calendering treatment, printing treatment, dry lamination treatment, solution or melt coating treatment, bag-making processing, deep drawing processing, box processing, tubular processing, slitting as required Processing, etc.

The thickness of the multilayer structure (including the stretched ones), and the thickness of the EVOH resin composition layer, the substrate resin layer, and the adhesive resin layer constituting the multilayer structure will depend on the layer composition, the type of substrate resin, and the adhesiveness. The type, use, packaging form, and required physical properties of the resin vary, and it cannot be generalized. The thickness of multilayer structures (including stretched ones) is usually 10 to 5000 μm, preferably 30 to 3000 μm, and particularly preferably 50 to 2000 μm. . The EVOH resin composition layer is usually 1 to 500 μm, preferably 3 to 300 μm, particularly preferably 5 to 200 μm, and the substrate resin layer is usually 5 to 3000 μm, preferably 10 to 2000 μm, particularly preferably 20 to 1000 μm. Adhesion The resin layer is usually 0.5 to 250 μm, preferably 1 to 150 μm, and particularly preferably 3 to 100 μm.

In addition, the thickness ratio of the EVOH resin composition layer to the base resin layer in the multilayer structure (EVOH resin composition layer / base resin layer). When there are a plurality of layers in each layer, the thickness of the thickest layer is the thickness of each other. The ratio is usually 1/99 to 50/50, preferably 5/95 to 45/55, and particularly preferably 10/90 to 40/60. In addition, the thickness ratio of the EVOH resin composition layer to the adhesive resin layer in the multilayer structure (EVOH resin composition layer / adhesive resin layer). When there are a plurality of layers in each layer, the thickness ratio of the thickest layers to each other is used. It is usually 10/90 ~ 99/1, preferably 20/80 ~ 95/5, and particularly preferably 50/50 ~ 90/10.

Containers and lids made of bags, cups, trays, tubes, bottles, etc. made of the films, sheets, and stretched films obtained as described above are useful as mayonnaises and dressings, in addition to being useful as general food packaging containers. Various packaging materials such as seasonings, fermented foods such as miso, oils such as salad oil, beverages, cosmetics, and pharmaceuticals are also useful. In particular, the layer composed of the EVOH resin composition of the present invention has excellent ultraviolet absorbing ability, and is therefore particularly suitable as a packaging material for food, and particularly as a packaging material for meat such as meat, ham, and sausages where discoloration due to ultraviolet rays is likely to cause problems. it works. [Example]

Hereinafter, the present invention will be specifically described with examples, but the present invention is not limited to the description of the examples as long as it does not exceed the gist thereof. In addition, the "part" described in an example means the basis of weight, unless otherwise stated.

[Ultraviolet Absorptivity] A 5% by weight water / isopropanol (4/6) solution was prepared using the EVOH resin composition. Then, the UV transmittance (wavelength 300 nm) of this solution was measured using UV-VIS SPECTROPHOTOMETER (manufactured by Shimadzu Corporation, UV-2600). The ultraviolet transmittance of the pure resin composition itself can be evaluated by measuring the ultraviolet transmittance of the EVOH resin composition in a uniform solution state. The lower the value, the higher the ultraviolet absorption capacity.

[Coloring] An EVOH resin composition was thermoformed (210 ° C, melting time 5 minutes, compression time 30 seconds) using a manual hydraulic vacuum heating press (manufactured by Imoto Co., Ltd., IMC-11FD-A) to obtain 2mm thick resin board. The YI value of the obtained resin plate was measured using a color difference meter (manufactured by Nippon Denshoku Industries, SE 6000).

[Thermal stability] 5 mg of EVOH resin composition was measured using a thermogravimetric measuring device (manufactured by Perkin Elmer, Pyris 1 TGA) under a nitrogen environment: 20 mL / min, a heating rate: 10 ° C / min, and a temperature range: 30 ° C At a temperature of ~ 550 ° C, the temperature at the time when the weight was reduced to 95% of the weight before the measurement was measured.

<Example 1> As the EVOH resin (A), an ethylene-vinyl alcohol copolymer having an ethylene structural unit content of 44 mol%, a saponification degree of 99.6 mol%, and an MFR of 12 g / 10 minutes (210 ° C, a load of 2160 g) was used. The methanol solution (resin component concentration: 36% by weight) of the EVOH resin (A) was blended with an acetic acid aqueous solution to make acetic acid 1.5 parts per 100 parts of the EVOH resin (A). This methanol solution was transported by a gear pump, and extruded into a strand shape from a circular die into water, and cut into strand-shaped pellets.

The obtained pellets were brought into contact with an acetic acid aqueous solution (acetic acid concentration of 2200 ppm) at a bath ratio of 2.5 at 35 ° C for 3 hours, and then dried at 100 ° C for 36 hours in a nitrogen gas stream to obtain 44 mol% of ethylene structural unit and a degree of saponification. 99.6 mol%, pellets of EVOH resin (A) with MFR 12g / 10 minutes (210 ° C, load 2160g).

[Analysis of the iron compound (C)] 0.5 g of the sample obtained by crushing the pellets of the EVOH resin (A) was subjected to an ashing treatment in an infrared heating furnace (650 ° C, 1 hour in an oxygen gas stream), and the ash was dissolved. Use acid to make up the volume with pure water, and use it as a sample solution. This solution was measured by ICP-MS (ICP mass spectrometer 7500ce manufactured by Agilent Technologies) according to a standard addition method. As a result, the content of the iron compound (C) was 0.1 ppm in terms of metal.

Using a plasticity analyzer (manufactured by Brabender), 100 parts of the pellets of the EVOH resin (A) obtained above and 0.05 part of trans-cinnamic acid (manufactured by Wako Pure Chemical Industries, Ltd.) as a styrene derivative (B) were prepared at 210 ° C. After preheating for 5 minutes, it was melt-kneaded for 5 minutes. The obtained kneaded material was cooled, and then subjected to a pulverization treatment to obtain an EVOH resin composition. The evaluation was performed on the EVOH resin composition. The results are shown in Table 1 described later.

<Comparative Example 1> An ethylene-vinyl alcohol copolymer (iron compound (C)) containing 29 mol% of ethylene structural unit, 99.6 mol% of saponification, and 3.9 g / 10 minutes (210 ° C, load 2160 g) was used. An EVOH resin composition was obtained in the same manner as in Example 1 except that the content was 0 ppm in terms of metal) as the EVOH resin (A). The obtained EVOH resin composition was similarly evaluated. The results are shown in Table 1 described later.

<Comparative Example 2> 100 parts of pellets of EVOH resin (A) used in Example 1, 0.05 part of trans cinnamic acid (manufactured by Wako Pure Chemical Industries, Ltd.) as a styrene derivative (B), and iron compounds (C) 0.0034 parts of iron (III) phosphate hydrate (manufactured by Wako Pure Chemical Industries, 230 ° C drying loss 20.9% by weight) 0.0034 parts Melt-knead at 210 ° C for 5 minutes using a plasticity tester (made by Brabender), After the kneaded material was cooled, it was pulverized to obtain an EVOH resin composition. The obtained EVOH resin composition was evaluated similarly. The results are shown in Table 1 described later.

<Comparative Example 3> An EVOH resin composition was obtained in the same manner as in Example 1 except that trans-cinnamic acid was not blended. The obtained EVOH resin composition was evaluated similarly. The results are shown in Table 1 described later.

<Comparative Example 4> An EVOH resin composition was obtained in the same manner as in Comparative Example 2 except that trans-cinnamic acid was not blended. The obtained EVOH resin composition was evaluated similarly. The results are shown in Table 1 below.

【Table 1】

Comparing Comparative Example 3 and Comparative Example 4 containing the iron compound (C) and not containing the styrene derivative (B), it can be seen that the ultraviolet absorption capacity is increased in proportion to the blending amount of the iron compound (C). The thermal stability is increased in proportion to the blending amount of the iron compound (C). In addition, when Comparative Example 2 and Comparative Example 4 are compared, it can be seen that when the iron compound (C) is contained at 10 ppm and the styrene derivative (B) is used in combination, a better ultraviolet absorption ability is obtained, and the thermal stability is equally good. , But the YI value is high, resulting in coloring due to heating.

In contrast, in Example 1 where the EVOH resin composition of the present invention was used, although the iron compound (C) was a trace amount of 0.1 ppm, the ultraviolet absorption capacity was the same as that of Comparative Example 2, and the coloring was more suppressed and the thermal stability was more improved. Promotion. On the other hand, Comparative Example 1 containing a styrene derivative (B) and not containing an iron compound (C) was inferior to Example 1 in terms of ultraviolet absorption ability. In addition, Comparative Example 1 had a higher YI value than Example 1, and coloration was caused by heating, and thermal stability was also poor.

In addition, in Comparative Examples 3 and 4 which do not contain a styrene derivative (B), although the blending amount of the iron compound (C) decreases, the thermal stability decreases. In Example 1, an unexpected effect was obtained that the thermal stability was not even impaired even if the blending amount of the iron compound (C) was low. It can be seen that this effect can be obtained only by using a combination of a styrene derivative (B) and a small amount of an iron compound (C).

The above embodiments have disclosed specific forms of the present invention, but the above embodiments are merely examples and are not to be construed in a limiting sense. Various modifications obvious to those having ordinary knowledge in the technical field are intended to be included in the scope of the present invention [Industrial applicability]

The EVOH resin composition of the present invention does not contain a general ultraviolet absorber, but still has ultraviolet absorption ability, excellent thermal stability, and suppressed coloring. Therefore, it can be used as a packaging material for various foods, and it can also be used as a Mayo Various packaging materials such as seasonings such as foods and sauces, fermented foods such as miso, fat foods such as salad oil, beverages, cosmetics, and pharmaceuticals.

Claims (5)

An ethylene-vinyl alcohol-based copolymer composition containing an ethylene-vinyl alcohol-based copolymer (A), a styrene derivative (B), and an iron compound (C), characterized in that the ethylene-vinyl alcohol per unit weight of the ethylene-vinyl alcohol In the copolymer composition, the content of the iron compound (C) is 0.01 to 5 ppm in terms of metal. For example, the content of the ethylene-vinyl alcohol copolymer composition in the first patent application range, wherein the content of the styrene derivative (B) per unit weight of the ethylene-vinyl alcohol copolymer composition is 1 to 1000 ppm. . For example, the ethylene-vinyl alcohol copolymer composition according to item 1 or 2 of the patent application range, wherein the weight ratio of the content of the styrene derivative (B) to the metal-converted content of the iron compound (C) is 0.2 to 50000. A pellet is composed of an ethylene-vinyl alcohol copolymer composition according to any one of claims 1 to 3 of the scope of patent application. A multilayer structure including a layer composed of an ethylene-vinyl alcohol copolymer composition according to any one of claims 1 to 3 of the scope of patent application.